


Not Quite Identical

by unmotivatedmillennial



Category: Adventure Time
Genre: Adventure Time - Freeform, Finncest, I love my rowdy boys, M/M
Language: English
Status: Completed
Published: 2020-03-12
Updated: 2020-04-03
Packaged: 2021-02-28 19:20:36
Rating: Mature
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 4
Words: 6,406
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/23112352
Author URL: https://archiveofourown.org/users/unmotivatedmillennial/pseuds/unmotivatedmillennial
Summary: Finn learns that Fern's body differs from his in more ways than just being green. The realization makes very him curious about a certain part of the grass boy's anatomy. Will Finn’s attempt to know more about his doppelganger change the way he sees him?
Relationships: FerntheHumanxFinnMertens, FerntheHumanxFinntheHuman, FernxFinn, FinnMertensxFerntheHuman, FinntheHumanxFerntheHuman, FinnxGrassFinn, GrassFinnxFinn, finnxfern
Comments: 20
Kudos: 151





	1. Chapter 1

Finn followed his grass double into the kitchen, completely ignoring the fact that Fern was trying to get away from him. Fern slumped down to have a seat at the kitchen table and Finn plopped down beside him.

"Come on. Just for a second?"

Fern put his face on the table, then covered his head with his arms.

"No, Finn. It's weird," he said, his voice muffled as he wasn't bothering to lift his head from the table.

Finn crossed his arms on the table next to him and laid his head down on top of them, looking at Fern through the gaps in the grass boy's own arms.

"Tell me how it's weird," he demanded, skeptically, "We're basically the same guy."

"It's just weird, dude! Get away from me!" Fern shouted, shoving Finn and getting up from the table to pace around the kitchen.

Finn and Fern had been going back and forth in this way for close to 10 minutes. Their argument traced back to the other day when Jake had suggested they see if Fern could fold his tongue (Finn was the only organic being they knew who couldn't do it). Not only had Fern been able to curl his tongue, but he could elongate it and change its shape into something snakelike. Since then, Finn had become obsessed with figuring out what other ways their bodies differed from one another.

"But, it's just us now. BMO's at soccer practice til 6 and Jake won't be back from Lady's for days. Nobody's gonna walk in on us."

"Do you hear yourself?!" Fern shouted incredulously, throwing his arms up in the air.

"What?" asked Finn, innocently.

"Walk in on us? You're making it sound even grosser than it already is!"

"It's not gross," Finn scolded, defensively, "It makes sense that I would wanna see it, Fern. We're curious by nature. You know this!"

The plant boy rolled his eyes.

"I don't care!" he exclaimed, completely fed up, "I don't care why you wanna see it, because I am not showing you my thing!"

Finn slid out of his seat and onto the floor, lying on his back underneath the kitchen table.

Fern sighed before getting on hands and knees to check on the other him.

"You really gotta let this go, man. It's not healthy," Fern consoled him, placing a hand on his shoulder.

"I can't, man. Not knowing is gonna bother me until the day I die," the blond teen replied solemnly.

"You sound like a real D-list right now, Finn. Let's get up from here. The floor is filthy," Fern said, making a face.

"I know, right?" Finn said grinning, quickly recovering from his dramatics. "I call not sweep the floor!" they both yelled quickly as they climbed out from under the table.

They both chuckled and pinched each other three times as they got to their feet. The first time for a laugh and the second to get the other one back for pinching them. Then, once more for another laugh.

"It's been dirty since way before I got here. I can remember the last time Jake swept," Fern reasoned, still chuckling as he walked over to the corner to grab the broom and held it out to Finn.

"Fine," Finn said grudgingly, "I'll sweep... if you show me."

Fern pushed the broom into Finn's chest, annoyed.

"No," he said flatly before walking away, leaving Finn to his chore.

...

After Finn had finished sweeping, he went ahead and started on the dishes that had been piling up.

Was he being weirdly obsessive about this? He was sure Fern's thing was different from his. He could tell by the way the other boy acted when he asked. But why did it matter? Finn wiped off the last glass and put it away before drying his hands.

By the time he made it upstairs, his doppelganger was sprawled out on the purple couch, his feet hanging over the side. He was halfway asleep.

Finn sat down on the floor, cross-legged in front of him.

"Okay, dude. Hear me out one last time, then if you're not convinced, I swear I'll drop it."

Fern turned onto his side to face the back of the couch, turning his back to Finn.

"Are you seriously doing this right now? I'm trying to take a nap," he mumbled grumpily.

"Fern, I'm sorry for bugging you so much over the past few days. I know you think it's stupid, but this is actually really important to me. Just let me try to explain one more time, then I'll let you sleep and I won't bother you again."

When Fern turned around Finn was looking at him with puppy dog eyes. The plant boy had tons of memories of employing that exact look to get Jake to go on quests when his brother had decided he'd rather stay home and play BMO. It was weird to have it used against him like this. Then again, everything was weird now that there were two of them.

"Fine, Finn," Fern caved, "Five minutes. And if this is some kind of game and you're wasting my nap time, I'm gonna bop you one."

"I agree to those terms!" Finn said excitedly, adjusting himself and getting comfortable in preparation to make his case.

"Okay, so we're the same, you know? We both remember everything that's ever happened to us up to the point where you came outta Finn Sword."

"Sure," Fern conceded sounding bored.

What was Finn's point? They had deduced that much weeks ago.

"You know things about me that know one else knows, not even Jake, cause they're also things about you, right?"

Fern nodded, beginning to understand what Finn was getting at.

"So, both of us know every dumb, gross, embarrassing thing the other one has ever done. Everything we've ever seen or felt. We can talk to each other and know the other one's gonna understand, because he already experienced the exact same thing. Nobody else has somebody like that. Not twins, not clones, not even mirror peeps from other dimensions. Just you and me, Fern. It's kind of amazing."

Finn was looking up at him so intently that Fern had to look away.

"But, I guess, we're not really the same person anymore since you came outta Finn Sword," Finn continued, "You're green and you can do all this rad stuff and the new memories we make, we don't share those like the old ones. If we're gonna keep understanding each other better than anyone else, we have to tell each other everything from now on and not keep secrets. Otherwise, we're gonna lose this really cool and special thing we have and I don't wanna do that. I've really loved having someone who's even closer to me than a brother, and I don't want to grow apart and leave that behind."

Fern's face softened as he looked down at his other self. He grasped the human boy's shoulder.

"Finn... all of that was really sweet. I know you were speaking from the heart and I guess I feel the same way... but, you need to tell me the real reason or I'm gonna bop you one."

Finn groaned and wriggled out of Fern's grip.

"Okay! " he said frustrated at being called out so plainly, "Okay, fine, here goes. You have literally one gazillion memories of my thing from like peeing and baths and private time across, like, our whole life. So, of course you know what it looks like. It’s still the same. But, now you've got a new grass boy ding-a-ling and I have no idea what it looks like because you won't show it to me and it's not fair!"

Finn sulked, silently, on the floor after finishing his rant.

Fern sat up on the couch and closed his eyes, massaging his forehead.

"Okay," he said quietly.

"Okay?" Finn repeated, his face perking up at once, "I can see it?!"

"Yeah. I'll show it to you... IF I get to sleep in the bed for three months."

Finn's face fell a little.

"How about one month," he bargained thoughtfully.

"Three months, Finn," Fern replied, stubbornly.

Finn didn't love the idea of giving up his bed. But, to be fair, in a way it was Fern's bed, too. And it had to be hard for the grass boy sleeping on the couch all the time. More importantly, Finn was dying to know what Fern's thing looked like.

"Deal," the blond said, holding out his metallic hand.

"Deal."

Fern grabbed his hand shook it, before climbing off of the couch.

"Where do you think you're going? Drop them shorts, boi!" Finn demanded eagerly.

Fern roll his eyes.

"C'mon, psycho. We're going upstairs. I'm going to bed the second I hold up my end of the bargain."

Finn saw no issues there, so he hopped up and followed Fern up the stairs to his and Jake's bedroom.


	2. Chapter 2

When Finn reached the top of the stairs, Fern was pulling his shirt over his head.  
“Good idea, man!” Finn said encouragingly. “Just get naked, then I can check your whole body.”  
Fern balled up his grass shirt and lobbed it at the human boy’s head.  
“No, dude, I’m just changing into my pajayjays. Turn around,”  
“Oh,” Finn chuckled at his mistake and obediently turned his back to the other boy. “But you know, it would make sense for you to just...”  
Finn cut off mid sentence as a pair of shorts woven from grass fibers nailed squarely in the back of the head.  
“Finn, I swear to glob...” Fern warned, testily.  
The blond boy laughed again, but said nothing else.  
“Okay, you’re good,” Fern called from the other side of the bedroom. He was wearing one of Finn’s red pajama onesies and had taken off his hat, his long, golden green hair flowing freely.  
“Wow, Fern,” Finn said, impressed. “I’ve never seen you wear anything but your grass clothes. You look good, bro.”  
Fern struck a ridiculous flexing pose with his arms to make Finn laugh.  
“Thanks, guy,” the grass boy said appreciatively, “Now come here so we can get this over with.”  
Finn practically skipped over to where Fern was sitting on the bed rubbing his hands together excitedly.  
Fern leaned back and kicked him in playfully in the side.  
“Wow, Mertens. You’ve gotta stop being such a weirdo about this, like, right now,” he said making a face.  
Finn grinned guiltily.  
“I can’t help it, Fern. By not letting me see it when I first asked, you built it up too much. Now, the suspense is killing me,”  
Fern rolled his eyes again.  
“Whatever, dude,” he said, giving up. “Okay, I’m gonna lift the jammy flap so get a good look and then we never speak of this again. Got it?”  
“Understood,” Finn replied seriously.  
Fern felt extremely weird about how intently the human boy was staring at his crotch, but he guessed there was no helping it. He reach down and adjusted himself out of his pajamas so that his penis was visible. Apprehensively, he watched the blond boy’s reaction.  
Finn’s jaw nearly hit the floor.  
“Fern...,” he exclaimed, “ You’re huge!”  
Finn had kind of expected this to be the case. But, now that he was actually seeing it, he was shocked at how much larger Fern’s was than his.  
Fern looked away feeling extremely self-conscious.  
“I didn’t want you to feel weird because it’s bigger now, for some reason. It’s actually kind of annoying...” Fern trailed off, embarrassed.  
Finn took a step closer to get a better look. The shape of Fern’s penis was very similar to his, only larger and thicker. It was also a darker green than the rest of his body. Although, Finn conceded to himself that the skin of his own penis was like that as well.  
“If you’re this big how come, you don’t see it through your shorts?” Finn asked, thoughtfully, still studying Fern’s member with the deep interest of an archaeologist.  
The blades of grass that made up the tufty patch that Finn assumed served as Fern’s pubic hair elongated, wrapping around Fern’s member and then entangling with the sparse blades at the base of his abdomen, holding him upright and in place.  
“You do that all day?” Finn asked incredulously.  
Fern nodded, still feeling too awkward to meet his eye.  
“That’s insane,” Finn said sympathetically. “Okay, dude, show me the other bits,” he said expectantly after a moment, nodding to a point lower on Fern’s crotch.  
“What?!” Fern shrieked , “Uh-uh, bro. I showed you my thing and now we’re done.”  
He reached down and attempted to redress himself, but the human grabbed his arms to stop him.  
“No way, man,” Finn argued as the other boy struggled to get out of his grasp. “I gave up my bed for 3 months so I wanna see the whole Fern-boy package.”  
“Are you crazy? Get off of me!”Fern jerked out of Finn’s grasp so that the human had to put both hands out on the bed on either side of him to keep from falling over. As soon as he caught himself, Finn was geared up to yell at Fern for cheating on their deal, but he stopped when he saw the grass boy’s face.  
“Fern are you okay?” he asked, concerned.  
The plant boy’s nose and cheeks were a shade of scarlet that rivaled his pajamas.  
From so close, Finn could see that the blush was actually hundreds of tiny red and pink flowers blossoming on Fern’s face.  
“I told you to get off me,” he said quietly, tucking himself back into the pajamas and redoing the buttons.  
“Does it hurt?” Finn asked, still sounding worried.  
Fern shook his head.  
“They go away after a while,” he said, staring at his hands which were now folded in his lap.  
“They smell kinda ... nice,” Finn said leaning in closer and inhaling deeply.  
Fern scooted further back on the bed, away from the other boy.  
“I hadn’t noticed,” he muttered darkly.  
“Wait, you’ve been like this before?” Finn asked, finally registering what the grass boy had said.  
The human boy was way too close for Fern’s liking, but suddenly he felt too nervous to push him away.  
“Yeah, once,” he admitted.  
“Well, what happened?”  
Fern turned away from the other boy as much as he could. Not much considering their current positioning.  
Finn just leaned closer forward.  
“You already know I’m gonna get it outta you,” Finn reasoned, smugly.  
Fern groaned and plopped backward onto the mattress, covering his still crimson face with his forearms.  
Finn clambered onto the mattress and straddled Fern to sit on top of his thighs. He pushed the plant boy’s arms up just enough the uncover his mouth, but otherwise left him be.  
“Well?” Finn said expectantly.  
Even though Fern’s face was partially obscured, Finn could see that the flush was spreading, creeping outward toward his ears.  
“I was thinking about makeouts...,” he said, barely audibly.  
Finn skipped a beat, then snorted so hard he almost fell over and had to scramble to catch himself.  
“You were thinking about makeouts and you started blushing? That’s not a big deal, Fern,” he said, still laughing.  
“No,” Fern continued exasperatedly. “I was thinking about makeouts and how I have all these memories of girls... doing things. And they don’t even know I have them...”  
“Wow, I guess I never thought about it like that...,” Finn mused.  
Fern made a pained noise.  
“But it’s not your fault, Fern. It’s not like you chose to remember that stuff,” Finn offered, trying to cheer him up.  
Fern groaned again but said nothing.  
“Well, okay...,” Finn said trying a new tack. “When you remember that stuff, is it like you just know that it happened or...”  
“It’s like I’m there and it’s happening to me.” Fern interrupted him, finally uncovering his face and looking at the other boy. “I see it through your eyes, Finn. Everything they showed you and thought only you would see. Oh, glob, and I can hear how they sounded and what they said to you. Things they didn’t mean for anyone else to hear. And I... I feel what your body felt like when you were doing things with them... how good it felt...”  
The flush was spreading up Fern’s neck and across his chest and scent of his flowers now filled the room. Without realizing it, Finn’s breathing had become heavier.  
He bent over to wipe away the tears that were rolling down the sides of Fern’s face and into his hair.  
“You don’t have to feel guilty about the way you felt when you remembered that stuff. They’re your memories. You’re Fern now, but you used to be Finn. You didn’t do anything wrong.”  
Fern stared up at him. Tears still welled in his eyes, but his expression was grateful.  
Finn grinned down at him and soon Fern was grinning, too. Relieved that his other self was feeling better, Finn dropped down to hug him.  
“You see, Fern?” he said reassuringly, “Us same bros gotta stick together. You can tell me anything, alright?”  
“Alright,” Fern agreed, still grinning.  
He had to admit that the hug felt nice, but he would have expected Finn to get off him by now. Instead, the human boy squeezed him tighter.  
“Why do you smell so good, Fern?” the blond asked close to his ear.  
Just as the flush had started to fade, he could feel his face heating up again.  
“It must still be my flowers,” he said awkwardly, “I can’t really smell them.”  
“They smell amazing.”  
The human boy rested his head on Fern’s shoulder.  
“Uh, Finn?” Fern asked uncertainly.  
“Don’t make me move. I wanna stay like this,” Finn murmured against him. “So good...,”’he sighed.  
The way Fern had blushed before was nothing compared to now. Patches of red covered his face all the way up to his hairline. He peeked to his side at Finn to see that the other boy was extremely flushed now, too. His eyes were closed and his expression was relaxed.  
“Finn, I think you should get off me,” Fern warned nervously.  
“Why?” Finn sounded half asleep, his voice muffled against Fern’s shirt.  
“I just don’t think we should be doing this, is all,” Fern said, trying to keep his voice level.  
Fern’s body jolted as Finn began nuzzling against his neck.  
“But, it’s nice,” he whispered in the grass boy’s ear. “You think it’s nice, too, right?”  
Fern ignored his question.  
“Finn, I think my flowers might be doing something to you,” he said, concerned.  
“Yeah, maybe,” Finn contemplated, still snuggling against his neck. “Your flowers smell so good, Fern. But, the truth is, I’ve thought about stuff like this before. When I found out we have the same memories I wondered if you thought about doing stuff that feels nice. Like, I wondered if when you remembered touching yourself, you thought about how it’s really like you were touching me. Does that make sense?”  
Fern gulped and nodded. He actually had thought about it exactly that way on several occasions.  
“I kinda thought so,” the human boy whispered.  
Finn raised himself up to look Fern in the eyes. The grass boy looked apprehensive, barely meeting his gaze. But Finn recognized longing in his expression, too, and that told him what he needed to know.  
He leaned down and pressed his lips against Fern’s.


	3. Chapter 3

Fern's whole body tensed underneath him. The grass boy's eyes were shut tight and his expression was strained. Finn used his metallic hand to prop himself up and the other to cup Fern's face. With his calloused thumb, he stroked the plant boy's flower covered cheek as he continued to press their lips together. Finn felt the tension slowly leave the other boy's body until Fern actually sighed and began kissing him back.

Fern's lips were cool and rough. The sensation was a bit unexpected, but not unpleasantly so. In fact, the feel of them was so nice that Finn couldn't stop himself from kissing Fern much more roughly than he'd meant to. The grass boy moaned quietly and the human took the opportunity to slip his tongue into Fern's mouth. Almost instantly, Finn gasped and pulled away.

"What?" Fern asked in alarm.

"You taste... sweet. Kinda like sap, maybe..."

Finn was still considering how exactly to describe the taste when he noticed Fern was frowning.

"Is it gross?" the plant boy asked, looking away from Finn.

Finn's eyes widened, shocked that his reaction had been so wildly misinterpreted. He kissed Fern hard and held the sides of the other boy's face in his hands before responding.

"Fern, you taste amazing. You are amazing," Finn said beaming down at him.

When Fern looked back up at him, his face was more cheerful but he still looked a little unsure. As if he was glad to hear what Finn had said but couldn't bring himself to fully believe it.

The expression made Finn's heart ache. He knew that if he had been through all of the uncertainties Fern had, he would be just as insecure as his grass double. I'll just have to keep showing Fern how much I want him until he gets it. He thought to himself, resolute.

He kissed his other self again, immediately sliding his tongue against Fern's. Somehow, he tasted even better than the first time. He let his natural hand wander, exploring the other boy's chest before coming to rest against his abdomen.

"So good...," he said happily into the other boy's mouth.

He couldn't get enough. His kisses became sloppier as he got more and more worked up, licking and biting Fern's bottom lip and at one point even sucking his tongue. The grass boy didn't seem to mind. Tentatively, he brought up his hand up and buried it in the human's soft hair. Finn sighed contentedly. He looked lovingly down at the other boy as he broke their kiss to drag his lips softly against Fern's forearm.

"You can touch me other places, too," he encouraged.

More flowers blossomed on Fern's cheeks before Finn's eyes. So dang cute, the human boy thought happily. Finn began placing kisses against his doppelganger's neck, seeking out the parts where he himself was sensitive on the other boy's body. He dragged his tongue across the spot where Fern's jaw met his neck before licking and pulling lightly at the plant boy's earlobe with his teeth. The blond teen enjoyed the sighs and gasps he earned from his grass double as he simply did all the things he liked having done to himself.

"Finn, are you *hah* are you sure we should be doing this? We're both... *mmm*... Isn't this kind of weird?"

Finn wasn't discouraged. Fern's breathless tone didn't match up at all with what he was saying. His voice hitched and little moans slipped out as Finn continued marking him with love bites.

"It's not weird, Fern, it's natchy," the human boy said innocently before pulling back to look his other self in the eyes. "We're just two of the same dude making each other feel good."

The blond pressed a soft kiss against the other boy's lips before nudging his knee forward in between his legs. Fern gasped and his hips gave and involuntary jerk. His eyes were wide and he was gripping Finn's hair so tightly that it was painful. The human reached up and pulled his hand away, kissing Fern's palm before positioning the plant boy's hand on his own hip.

"It feels good, right?" Finn asked much more quietly.

The plant boy stared up and him and nodded shyly. His eyes were still wide and he looked a little afraid, but Finn could feel his erection growing against his leg.

"It's okay, Fern. I'm always gonna take care of you," he said tenderly.

Fern closed his eyes and nodded again. Finn kissed him on the forehead before pressing his knee more firmly against Fern's hard-on. Fern whimpered and his blush grew even more pronounced. Finn recaptured Fern's mouth with his and began massaging the plant boy's chest. Fern had begun to rub rhythmically against his leg now and was making such erotic sounds that Finn could barely stand it.

"Glob, Fern," Finn cried out, overcome. "You're so sexy it's crazy."

Instead of responding, Fern pulled him down for another kiss, elongating his tongue and massaging it against Finn's. So fucking hot, Finn thought. It was beginning to be too much. Fern tasted so good and there was still the delicious scent of his flowers, not to mention the way blood was rushing to his crotch. It was all making Finn feel very woozy. Fern was just as hard as he was so he knew the other boy must be in a similar state. Reluctantly, he broke the incredible kiss.

"C'mere," he said as he guided Fern to the head of the bed and laid him back down.

Fern watched him silently, eyes huge, as Finn crawled in between the grass boy's legs.

"What are you doing?" he asked the human nervously.

Finn didn't answer for a moment. He remembered when Jake had first told him that sometimes while making love partners used their mouths on each other down there. Although, he could imagine why the sensation would be enjoyable, at the time he had found the idea kind of off-putting. Suddenly, though, it made perfect sense. He was dying to watch Fern's face and hear the sounds he made as he kissed his most sensitive place. Finn began to unbutton the flap of Fern's pajamas. The plant boy's hips jerked again as Finn's hand grazed his scrotum.

"It's uncomfortable, right?" he said, referring to Fern's erection which had sprung free from the garment.

"Dude, it'll go away on it's own. You seriously don't have to..." Fern started, but Finn cut him off.

"I want to!” he said excitedly "Let me take care of that massive, grass boy ding dong for you."

Fern's face colored all over again.

"Finn, you moron..."

"It’s supposed to feel really good, but if you hate it, I'll stop. I promise," Finn reassured him as he lowered himself so that he was eye level with Fern's massive thing.

Fern's only response was to cover his face with his hands.

He wrapped his left hand around Fern's penis and began stroking it slowly and rubbing his thumb over the head. The plant boy whimpered. Finn looked up to see his expression and was amused to find that Fern was watching him through gaps in his fingers, his face showed an adorable mix of lust, embarrassment and disbelief. Finn smiled. Looking directly into Fern’s eyes, he slowly licked the head of his cock before taking as much of it as he could into his mouth. The other boy groaned and swore, closing his eyes and arching back away from the mattress. Finn had never seen a sexier sight. While still stroking the base, he bobbed his head up and sucking eagerly at the top half of his double’s penis. Because Fern was so large, the act of going down on him was more difficult than Finn had anticipated and he had to stop for breath more times than he would have liked. But the sounds the other boy made and the way his fists were clenching the furs on the bed made the effort more than worth it.

“Oh glob, Finn, it feels so good,” Fern moaned, his low voice even deeper with lust.

Finn sucked him harder in response, pumping his fist more quickly as he slurped at the head of his cock. Fern’s hips jerked and Finn had to hold him still to keep his rhythm and keep from choking.

“Finn, it’s too much... glob, you have to stop or it’ll come out,” Fern gasped suddenly.

But Finn kept his pace. He wanted to feel Fern’s thing pulse against his tongue and watch the other boy’s expression as he came. Fern’s hips were bucking again and Finn didn’t stop him, letting the other boy thrust into his mouth. Fern groaned in deep satisfaction and twisted his fingers into Finn’s hair as he came.

Finn gulped down what he could of the thick substance that exploded against his throat before pulling away. Fern’s cum was sweet just as his mouth had been and smelled the same as his flowers.

“Finn, I’m so sorry!” Fern apologized frantically.

He scrambled down to kneel next to the human, holding Finn’s face in his hands.

“It felt so good my mind went blank and I couldn’t stop,” the grass boy explained looking mortified. “Are you okay? I’m so, so sorry.”

Fern was gazing at Finn on the verge of tears. But Finn only grinned, wiping off a bit of Fern’s semen that had spilled out onto chin with his finger and sucking it clean.

“I told you it would feel good, didn’t I, Fern-boy?” he asked with an expression of smug satisfaction.

Fern’s eyes widened in relief, the tears that had been threatening to fall finally spilling over. He lunged at Finn, knocking him over and kissed the human forcefully.

“It felt better than good. Better than amazing,” he said lauging and wrapping his arms around the blond.

Finn beamed as Fern squeezed him and planted little kisses all over his face.

“I’m glad I got to take care of you,” Finn said happily, relishing all of the affection.

“Me too, Finn-boy,” Fern admitted snuggling his cheek. “But now it’s my turn,” he said pulling away to look at the human with a devilish glint in his eyes.


	4. Chapter 4

Fern pushed Finn, forcefully, onto his back. He felt slightly deranged. It was like everything the grass boy had been secretly longing for was before him on a silver platter and he was suddenly ravenous.

He propped his arms up on either side of Finn's head and stared hungrily down at the other boy. Fern was nearly in a state of frenzy, but Finn didn't look at all taken aback. Actually, the human's expression showed nothing but desire as the beautiful blond smiled up at him expectantly. At the sight, a dam inside Fern burst. He kissed the other boy passionately before biting down so hard he broke the skin. Finn gasped as Fern sucked at the blood that was beading up on his lip, but the way he was grinding against the plant boy showed that he enjoyed it more than a little.

"I want you to belong to me. I won't let anyone else have you," Fern growled in the human boy's ear after licking the wound clean.

Finn shivered and without skipping a beat, Fern slipped his hand into the blond's shorts, grabbed his throbbing penis and began stroking it slowly. 

Finn groaned contentedly against his lips before pulling him into a kiss toe-curling kiss. 

Fern could have stayed in the kiss forever with Finn's extremely sexy voice echoing around his head. But there were other parts of the human that he wanted to taste and other pleasures he wanted to show him. Taking a cue from his double, Fern held eye contact with Finn as he positioned himself in between the blond teen's legs.

"Don't force yourself, Fern. You don't have to do it just because I did," Finn said, his voice was uneven as he tried, unsuccessfully, to mask his excitement and lust for the sake of his beloved doppelgänger.

"Don't worry, Finn. I'm not forcing myself," Fern reassured the other boy suggestively.

Through the fabric of his shorts, Fern nuzzled his nose against the base of Finn's dick as his hand moved up and down over the shaft. Fern grinned up at the blond as his lover stiffened further. The next instant, the grass boy was pulling the human's shorts down and off. He replaced his hand and continued to tug at Finn's erection as he took in the sight of his penis hungrily. 

"You've never been this hard before," Fern noted with obvious pleasure.

Finn shook his head looking a little shy for the first time.

"This feels better than anything else I've ever felt," the human boy admitted.

The possessive pride the grass boy felt brought an almost demonic gleam to his eye.

"Good," he whispered, letting his lips brush against Finn's cock as he spoke. But, I'm just getting started."

Fern pressed his tongue firmly against the base of Finn's cock and slowly licked his entire length. When he reached the top he wrapped his lips around the head of his cock and began massaging his tongue against it.

Finn moaned long and low. The human's body tensed and his hips jerked a little as his double applied his supernaturally gifted tongue to different parts of Finn's penis. Because he could modify his shape, he was able to fit the whole of the human's member into his mouth with ease. He didn't need to breathe so his movements were maddeningly relentless as he bobbed up and down on Finn's erection. Fern was so amazing that a tiny part of Finn felt guilty about selfishly receiving such indescribable pleasure. But that section of his brain wasn't nearly as vocal as the rest which was repeatedly reminding him that the world would literally end if his lover stopped sucking him off.

"I'm gonna cum any second, Fern," Finn whispered, pleasure-dazed. 

But Fern shook his head and slowly pulled away. 

"Not yet," he said mischievously, "I wanna try something.

Something about the grass boy's expression made Finn gulp nervously, but he nodded his consent.

Gazing into his lover's eyes, Fern slowly lowered his head and placed a soft kiss against the side of Finn's cock. He licked and sucked at the spot for a moment before stretching his tongue against Finn's penis, elongating it and wrapping around the human's privates like a vine wrapped around a tree. Once he had converted the muscle into a sleeve, he slid the green coils up and down, licking every part of the human's member at once.

Finn cried out and tears of pleasure began to well in his eyes. Panting and whimpering, he breathlessly whispered Fern's name as he clenched fistfuls of the bed's fur pelts in his hands and thrust repeatedly against the other boy's tongue.

"It feels like my thing is melting, Fern," he whispered frantically. "It feels like I'm gonna go crazy."

The grass boy only smiled as he used his tongue to pump his lover's cock faster. The speed of Finn's thrusts increased as well. His eyes were squeezed shut and he was whispering a string of swears and frantic pleas. Within seconds, the entire lower half of Finn's body began to tingle. Fern felt his muscles tense and hurriedly took the human's penis back into his mouth. Finn came violently, his hips bucking erratically. Fern continued pumping him with his tongue to coax out every last drop of semen. He swallowed it all hungrily and grinned his sharp, crooked grin up at Finn once he was done. 

It was so incredibly sexy the human couldn't help but swoon. He pulled his double up to lay on top of him.

"That was unreal, Fern," the human panted, breathlessly. "I seriously thought I might die it felt so good."

Fern smiled into the human's neck, happy of the lavish praise.

"At first I was gonna hold back since it was the first time I'd tried anything like that. But, you sounded so sexy calling my name I just lost it. I wanna hear you say it even more."

"Fern. Fern...," Finn looked up at him, punctuating each utterance with a kiss. On the plant boy's forehead. His eyelid. His cheek and firm against his mouth. "Fern... Fern... Fern..."

They kissed for a long time. Both savoring the taste of the other, committing it to memory. As close as they were, as similar, there was still so much to learn about each other's bodies. They both relished the idea of spending long hours doing just that. 

After what felt like blissful ages, Fern pulled away from the kiss.

"I really love you a lot, Finn," he said gazing adoringly down into the other boys eyes and softly stroking his cheek.

A tear's began to roll down the human's cheek. Fern wiped several more away before he realized that some of them were his own, falling on to Finn's face as they wept.

"I love you, too, Fern-boy," the human whispered happily. "I'm never gonna let you go. When we're older, we'll get married and we'll be together forever."

"People will think that's weird, Finn. We're the same... you should marry a princess. That's what heroes..."

"I don't care what people think. I'm going to marry you, Fern. I love you and I don't ever want to be apart," Finn interrupted him, determined. "You wanna be with me, too, right?"

"For ever and ever, Finn-boy," Fern said grinning broadly.

Finn took the hand that was resting on his face, brought it to his mouth and kissed it all over.

"It's settled, then," he said in between smooches. "You'll be my princess."

Fern snatched his hand away, laughing.

"Idiot. You're the princess," he joked, holding the human at bay as the blond began to wrestle him, grabbing his hands and trying to crawl on top of the grass boy.

"We can both be princesses, Fern. Besides, shouldn't fight, we just got engaged," Finn chided playfully once he finally overpowered the other boy, climbing on top of him and planting a kiss on his forehead.

"Fine," Fern said, flopping on the bed in defeat and pretending to pout. 

"Stop being so cute or I'll marry you right now," Finn warned.

"You gotta catch me first Princess Slowpoke," Fern taunted.

"You're already caught, dummy," Finn pointed out, quirking an eyebrow. 

But, Fern pushed the human off of him at took off down the stairs at full speed.

"Ooh, you done it now, Princess Boingloings," Finn laughed, sprinting off after him.

Snickering, the grass boy picked up speed as he heard Finn closing in on him. With his heart as full as it had ever been, he thought to himself that if this was what it meant to be Fern, he couldn't imagine having ever wanted to be anything else.


End file.
